User`s guide

Core Kernel Functionality

• The rcutree.rcu_fanout_leaf boot parameter allows the value of RCU_FANOUT_LEAF to be

increased but not decreased. (3.6)

• Firmware files can be loaded directly from the file system rather than from udev. (3.7)

• xattr support in cgroups allow run-time metadata to be attached to cgroups. (3.7)

• The disable_nmi command in kdb disables NMI-entry and releases the port. (3.7)

• Add a special serial console driver to allow the temporary use of an NMI debugger port as a normal

console via the nmi_console command. (3.7)

• RCU locking changes:

• Control grace period duration from sysfs.

• Make rcutree module parameters visible in sysfs.

• Allow an RCU lock to be placed in an extended quiescent state when the CPU runs in user space.

(3.7)

• Add system call to enforce that kernel modules are loaded only from a read-only cryptographically

verified root file system. (3.8)

• Applications can choose between using 1-GB and 2-MB huge pages. Typically, this feature is used in

conjunction with a NUMA policy. (3.8)

• Add option to allow assignment of a memory node as movable memory, which allows an entire node to

be hot-pluggable. (3.8)

• Add sysctl variables to tune checkpoint/restart in user space (CRIU) including specifying the ID of the

next IPC object to be allocated. (3.8)

• Introduce CRIU message queue copy feature so that all pending IPC messages can be retrieved without

deleting them from the queue. (3.8)

• Correct the implementation of hierarchy support for the freezer cgroup. If a cgroup is frozen, all its

descendants are also frozen. (3.8)

• Implement the PTRACE_O_EXITKILL ptrace() request. (3.8)

• Add the VmFlags field to /proc/PID/smaps output. Required by CRIU. (3.8)

• Add TIOCGPKT, TIOCGPTLCK and TIOCGEXCL ioctl() calls to obtain the package mode and locking

state of a pseudo terminal, and to obtain exclusive mode on a tty. (3.8)

• Add a module parameter to force the use of expedited RCU primitives, which can benefit some

embedded applications. (3.8)

• Allow selected CPUs to have RCU callbacks offloaded to kthreads to prevent or minimize OS jitter. (3.8)

• Provide support in sysfs to determine the maximum number of virtual functions (VFs) and Single Root

I/O Virtualization (SR-IOV) capable PCIe devices that are supported, and the methods that are available

for enabling and disabling VFs on a per-device basis. (3.8)

• Add a sysfs node to present the available frequencies for power management. (3.8)

• Add the PM_QOS_FLAG_NO_POWER_OFF and PM_QOS_FLAG_REMOTE_WAKEUP power management

QoS device flags. (3.8)